Green Sea Turtles and Migration

Green Sea Turtles and Migration

They are sea turtles with a carapace that is olive to black. So, why are they called green sea turtles (Chelonia mydas)? These sea creatures live in tropical and subtropical areas of the Atlantic and Pacific. They eat seagrasses along the shore by biting off the tips rather than pulling them up by the roots. By doing that, they keep the seagrasses healthy, and the green vegetation makes their body fat turn green, which is where they got their name. 

Green sea turtles migrate far from their feeding grounds to various remote islands where they lay their eggs. Many of them live along the coast of Brazil, and a large percentage of those lay their eggs on Ascension Island. Ascension is a small volcanic island 1400 miles (2250 kilometers) out in the Atlantic Ocean. Because the prevailing equatorial current runs from Ascension to Brazil’s coast, it takes the adult turtles 50 days to swim from Brazil to Ascension Island. They make the return trip in less than 30 days, swimming with the current.

We could ask, “What advantage does this migration have?” The answer is easy. Ascension Island has sandy beaches where the turtles can lay their eggs. There are few predators on the island, so the percentage of the eggs that hatch and survive is high. When the hatchlings are ready, they paddle out into the equatorial current and float back to Brazil. 

There are more challenging questions we might ask. How do these turtles locate Ascension Island? What caused them to go there in the first place? Can we explain this migration by chance? Researchers have made suggestions, but the answers remain unclear. Maybe the best answer is that God has provided a way for these slow and harmless creatures to survive. They keep the seagrasses healthy in their home areas while serving a role in the fauna of the isolated volcanic desert island called Ascension. Green sea turtles are part of God’s amazing web of living things.

— Roland Earnst © 2024